The objective of the research proposal is the study of gastrointestinal heminthiasis using Nematospiroides dubius in the mouse as a model. This model will be utilized to determine (1) the nature and role of humoral and cell-mediated immune reactions in the self-cure and protection phases, (2) the effect of gastrointestinal helminthiasis on the local and systemic response to heterologous antigens, and (3) the effect of genetic factors on the host response to this nematode. Methods employed will include passive and adoptive transfers, time-sequence studies, genetic crosses, and assessment of local and systemic immune reaction by means of a variety of immunological assays. BIBLIOGRAPHIC REFERENCES: Molinari, J.A., R.H. Cypess, B.N. Appel. Effect of Infection with Trichinella spiralis and BCG on Thymic Histology. Int. Arch. of Allergy and Applied Immunology. 48:1776-1783, 1975. Aronoff, S.C., D.R. Boggs, S.S. Boggs, and R.H. Cypess. Failure of Neutrophilia to Increase the Number of Neutrophils Entering a Peritoneal Exudate in Mice. Proc. Soc. Expt. Biol. and Med., 149:215-218, 1975.